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What Can Be Done to Protect the World’s Sinking Cities?

Tim Collins

Global sea levels are currently rising at unprecedented rates with the result that some of the world’s largest cities could be “underwater by the end of the century if action to protect them is not taken quickly”. Indeed, the World Economic Forum’s Global Risk Report estimates that by 2100, rising sea levels will threaten 200 million people who live in low-lying areas.  

It is not just small Pacific islands that risk going under but also highly populous global capitals such as Bangkok. Indeed, we have already seen the deadly effects of rising sea-levels as one fifth of Bangkok was reported to be underwater in 2011 when it was hit by monsoonal flooding, resulting in the deaths of 500 people. New Orleans in the US is afflicted by a similar predicament. Almost half of the city is already below sea-level with scientists estimating that some areas of the city are sinking by 40 millimetres per year.

What’s causing the sea level to rise?

The cause of the rise in sea levels owing to global warming is twofold. Firstly, increased temperatures cause polar caps and glaciers to melt and therefore add water to the ocean. Secondly, the volume of the seawater expands as it is warmed. As the US Department of Commerce highlights that as “the ocean is absorbing more than 90 percent of the increased atmospheric heat associated with emissions from human activity”, sea levels will continue to rise by almost 3.5 mm per year. This figure is increasing exponentially with many scientists arguing that sea levels could rise by as much as one metre per year by 2100.

What can be done to combat the rise in sea levels?

The World Economic Forum identifies three ways to combat these rising sea levels: (1) hard-engineering projects, (2) nature-based defences and (3) people-based strategies.

1. Hard engineering solutions

Hard engineering solutions include seawalls, storm-surge barriers, water pumps, and overflow chambers. The most famous of these is the Maeslantkering barrier and subsequent Delta Works system in the Netherlands. The gigantic 201-metre-long barrier swings open and close to physically block the sea when levels rise to an unacceptable amount. Since 1997, this barrier has successfully protected the whole of the Netherlands, of which a quarter lies below sea level. The Maldives have installed similar seawalls around their islands, fortifying low-lying areas with three metre walls and the government of Thailand has installed a 2600-kilometre canal network and central park which can drain 4 million litres of water into underground containers.

2. Nature-based solutions

Nature-based solutions also exist which as the UN Climate Action Summit importantly highlighted in September 2019, “can be five times more cost-effective than engineered structures at protecting against rising sea levels”.  Thus, in the US, local governments have been building “living shorelines” which include “wetlands with sea and marsh grasses, sand dunes, mangroves, and coral reefs” to protect coastal cities from rising sea levels and flooding. These systems act as natural barriers against increased sea levels and tidal waves. They are also more resilient than concrete seawalls against extreme storms and have the added benefits of improving water quality and increasing aquatic biodiversity in the region.

3. People-based solutions

People-based strategies involve the relocation of peoples and businesses in low-lying areas to safer regions. One way of achieving this is through ‘floating islands’. One company at the forefront of this method is the Seasteading Institute, an NGO which is in the process of developing and refining plans to build entire floating cities around the world, particularly off the coast of Pacific Ocean islands. These cities could thus form part of governmental ‘adaptation plans’ where victims of heightened sea levels can be moved to these safer floating cities. Less complex methods also exist, as the government of “Kiribati has purchased land in Fiji as a potential new home for its citizens and in the United States, US$48 million has been allocated to relocate the entire community of the Isle de Jean Charles in Louisiana, which has lost 98% of its land since 1955”. Indeed, this forced relocation has already occurred in Fiji, with the town of Vunidogoloa moving 1.5 kilometres inland to escape the detriments of rising sea levels to the original site of their town.  

It is not just small developing nations that are detrimentally impacted by rising sea levels but also some of the world’s richest and most populous cities. Thus, as the sea levels continue to rise it is the duty of all governments and industry leaders to continue to develop new methods to combat the phenomenon and protect the hundreds of millions of people who will inevitably be affected.

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